II4 Records of the Indian Museum. [VoL. XVIII, 
The specimens we have examined are also colourless and 
opaque and seem to be thicker than those of L. cor, but they are 
perhaps not so fresh. 
Measurements (in millimetres) and Proportions of Shells. 
Height = si 13 10°5 II 10°5 75 
Maximum diameter Bic 8 0°5 a 7'0 5°25 
Height of mouth FS: II 8:0 qs 725 6:0 
Maximum diameter of 
mouth ae aie 5°25 45 4°5 3°25 3°0 
Maximum diameter to 
height of shell pase sLesm Seal eelal D057 80-5 These 
Maximum diameter to 
height of mouth Ut ta QOO REL 77 aL sa 7 1272 Kee 
These measurements, few as they are, illustrate the variable 
character of the race. We do not, however, find it possible to 
draw any line between the forma typica and Mousson’s var. angus- 
tior, as narrowness of the shell and flattening of the are of the lip 
are by no means always correlated and shells with the arc of the 
lip flattened are mixed indiscriminately with those in which it is 
convex. The mouth, however, is as a rule narrower and more 
elongate than in the typical L. teneva, Kiister, and the shell seems 
to be more variable, some individuals departing from the forma 
typica more than others. (Kiister, however, only figures one 
shell). For these reasons we think it best to recognize the Meso- 
potamian race as distinct, though not specifically. Fully adult 
shells are perhaps more different than young ones. ‘The differences 
between the extreme types of the typical form of the race and its 
phase angustior and those between phases A and B of L. bactrt- 
ana are very much the same, but intermediate individuals are 
much more numerous. 
L. tenera euphratica is common along the banks of the lower 
Euphrates in both recent and subfossil deposits. Capt. Boulenger 
obtained a series of rather small shells in a marsh 5 miles north of 
Samara. 
Limnaea hordeum, Mousson. 
(Pl. XV; figs..4).53) 
1874. Limnaea hordeum, Mousson, Journ. de Conchyl. XXII, p. 42. 
1919. Limnaea hordeam, Annandale & Prashad, Rec. /nd. Mus. XVIII, 
p- 57, pl. vil. fig..5. 
We have found in the collection of the Indian Museum a shell 
(identified by Mr. H. B. Preston as Succinea bensom, var.). which 
we believe to represent the adult of this species. It was associated 
with a young shell of L. gedrostana under the same name and came 
from the banks of the Gaud-i-Zirreh in the Afghan desert, where 
it was collected by Sir Henry McMahon some years ago. This 
shell agrees better in dimensions with Mousson’s type than those 
we have hitherto examined but is slightly larger. It differs from 
young shells in having the body-whorl proportionately smaller and 
the mouth larger and broader and the lip thinner—differences that 
